The ocean weighs 1.4 quintillion tons. The biomass in the ocean weighs 10 billion tons. The plastic being added is 8 million tons (of which the US is just 72,000 tons.)
The plastic added by plastic bags in NJ is probably around 3,000 tons (assuming NJ is 10% of the US and that 40% of the plastic is from plastic bags.) That's equal to 3 billion grams of plastic (3 * 10^9.). Most of the plastic is smaller than a gram.
The ocean is equal to 1.4 trillion billion grams (1.4 * 10^24.) That's a ratio of 467 trillion: 1 (water to plastic.)
It takes 16 grams of cyanide to kill a person. (Well, not everyone, but about 85%.) If all the plastic NJ put in the ocean, was cyanide instead, you would have to drink the equivalent of 2 trillion gallons of seawater to die from cyanide poisoning.
If it was sarin (nerve agent), it would be far more dangerous of course. In that case, if your skin was exposed to 1.2 billion gallons of water, you'd be a goner.
So, I'm skeptical that hand-picked pictures of unfortunate sea life exposed to plastic before it disintegrates is representative of what happens in the ocean. And I am baffled by what scientists told NJ officials that their efforts would have any effect at all.
Otoh, I'm not baffled by what legislators wanted. There's never been a tax that politicians won't impose if voters accept a good song and dance.